Battery module system with degassing device

Abstract

The invention relates to a battery module system (1) comprising a battery module (2) with a battery cell (4) arranged in a battery housing (3), a cooling circuit (6) configured to cool the battery cell (4) by means of a circulating cooling medium, and a degassing device (7) configured to extract gases (G) that accumulate in the battery housing (3) during operation of the battery cell (4) from the battery housing (3). It is proposed that the degassing device (7) comprises a suction jet pump (70) configured to generate suction pressure using the circulating cooling medium as a motive medium and to extract the gases (G) from the battery housing (3).

Description

[0001] The present invention relates to a battery module system with the features of claim 1 and a motor vehicle with the features of claim 10.

[0002] High-performance rechargeable battery cells, such as those used as lithium-ion batteries for electric vehicles, are typically housed in sealed battery casings. The entire assembly, consisting of the battery casing and one or more battery cells, can be referred to as a battery module. During charging and discharging (or operation), a battery cell is subject to temperature fluctuations and, consequently, pressure fluctuations within the battery casing. To prevent casing deformation and leaks due to excessive under- or overpressure, pressure equalization elements, such as pressure equalization membranes, are incorporated into the battery casing. These membranes allow for pressure equalization between the interior of the battery casing and its surrounding environment.

[0003] The battery cells described above produce gases during operation, which must also escape from the battery casing. However, modern battery modules feature a large number of densely packed battery cells that expand under load, thereby hindering gas flow and / or the escape of gases via the pressure equalization elements. Furthermore, the resulting gases are often heavier than air and therefore tend to accumulate, for example, in constricted areas.

[0004] The object of the present invention is to provide a battery module system, in particular for a motor vehicle, in which the gases produced during the operation of the battery cell are removed from the battery housing in a simple, process-reliable and, in particular, demand-oriented manner.

[0005] This problem is solved by a battery module system with the features of claim 1 and a motor vehicle with the features of claim 10. Preferred features are the subject of the dependent claims. Further advantages and features can be found in the general description and the exemplary embodiments.

[0006] The battery module system according to the invention has: a battery module comprising a battery cell arranged in a battery housing, a cooling circuit designed to cool the battery cell by means of a circulating cooling medium, and a degassing device designed to extract gases that accumulate in the battery housing during operation of the battery cell from the battery housing, wherein the degassing device comprises a suction jet pump designed to generate a suction pressure using the circulating cooling medium as a driving medium and to draw the gases out of the battery housing.

[0007] The invention is based on the idea of ​​extracting gases that accumulate in the battery housing during operation, thus effectively removing gases that collect in constrictions or at the bottom of the housing. The pump required to generate the suction pressure is designed as a jet pump, driven by the cooling medium circulating to cool the battery cell, such as air, water, or another coolant. This eliminates the need for an electrical supply to generate the suction pressure, thus avoiding the need for additional electrical wiring. The existing components of the battery module system are largely used to generate the suction pressure, allowing the solution according to the invention to be implemented with minimal effort and energy efficiency.

[0008] A suction jet pump is a pump in which the pumping action is generated by a fluid jet (drive medium) that draws in and conveys another medium (suction medium) through momentum exchange. According to the invention, the cooling medium acts as the drive medium, while the gases produced during the operation of the battery cell constitute the suction medium. The suction jet pump can be installed in a supply line or in a return line of the cooling circuit.

[0009] In principle, all battery types that produce gases during operation which must be vented from the battery casing are suitable as battery cells, especially lithium-ion batteries or solid-state batteries (also known as all-solid-state batteries). The battery module is specifically a traction battery for an electric vehicle.

[0010] The cooling circuit is in particular a closed cooling circuit, i.e. the cooling medium flows to cool the battery cell in a closed cooling medium line section of the cooling circuit inside the battery housing, on the battery housing or in a near area of ​​the battery housing.

[0011] In a preferred embodiment of the battery module system according to the invention, the degassing device is designed to feed the gases drawn in by the suction jet pump to the cooling circuit, so that the gases are transported away via the circulating cooling medium. In other words, the drawn-in gases are mixed with the cooling medium so that they can be efficiently transported away via the cooling circuit.

[0012] In a further preferred embodiment of the battery module system according to the invention, the cooling circuit includes a collection container designed to collect the gases carried away by the cooling medium. The gases mixed into the cooling medium can thus be removed from it. In particular, the cooling medium has a higher density than the gases, so that separation between the drawn-in gases and the cooling medium is simplified. For example, the cooling medium is a liquid, e.g., water or another liquid coolant. If the collection container is only partially filled with cooling medium, the gases contained therein can rise to an upper region of the collection container and thus be separated from the cooling medium.Preferably, the collection vessel has a pressure relief valve designed to allow the collected gases to escape into the surrounding battery module system or into a separate collection container once a predetermined internal pressure is reached. Particularly preferably, the collection vessel is a coolant reservoir. The coolant reservoir, also called a coolant overflow reservoir or coolant expansion tank, is present in most cooling circuits for mobile applications and is designed to reduce the pressure in the cooling circuit via a pressure relief valve when the coolant expands due to increased temperature. By using the coolant reservoir as a collection vessel for the gas extracted from the battery housing, the existing components of the battery module system are used to a significant extent, allowing for efficient and energy-efficient gas collection.Modern vehicles often have cooling circuits with multiple coolant reservoirs, which, within the scope of the present invention, can function as collection tanks so that the gases can be efficiently collected and, if necessary, released through a pressure relief valve.

[0013] In a further preferred embodiment of the battery module system according to the invention, the degassing device has a suction line with an inlet in the battery housing and an outlet connected fluid-conducting to a suction media inlet of the suction jet pump. In particular, the outlet of the suction line is arranged outside the battery housing.

[0014] In a further preferred embodiment of the battery module system according to the invention, the degassing device includes a valve configured to open or close the suction line. In this way, a degassing process can be controlled as needed. Preferably, the valve is configured to open or close the suction line depending on the temperature of the cooling medium and / or depending on a temperature measured inside the battery housing and / or at predetermined time intervals. The operation of the battery cell, during which the gases to be extracted are generated, is associated with a specific temperature of the cooling medium or a specific temperature inside the battery housing, so that in some applications it may be advantageous to initiate the degassing process depending on the temperature.In particular, the battery module includes a control unit configured to open or close the valve of the degassing device depending on a predetermined condition. Specifically, the battery module system includes a temperature sensor that transmits a signal to the control unit and is configured to detect the temperature of the cooling medium and / or the temperature inside the battery housing. The control unit is configured to open the valve when a threshold value for the detected temperature is exceeded. Alternatively or additionally, the control unit can be configured to open the valve at regular intervals to ensure regular degassing of the battery housing.

[0015] In particular, the valve is integrated into the suction jet pump and features a closing element that can be moved between a closed and an open position by means of an actuator. The actuator contains a shape memory alloy and is designed to absorb heat from the cooling medium flowing through the suction jet pump and to move the closing element depending on the absorbed heat. Shape memory alloys (SMAs) are special metal alloys that can be deformed when cold but return to their pre-deformed ("remembered") shape when heated. This effect is based on the presence of a high-temperature phase called austenite and a low-temperature phase called martensite in such alloys.Due to the heat absorbed from the cooling medium and the resulting transition of the shape memory alloy into its high-temperature phase, the actuator changes its shape and acts on the closing element in such a way that the closing element moves and the opening is, for example, at least partially opened. In this way, a temperature-dependent switching of the valve can be implemented. In particular, the use of a separate temperature sensor for measuring the temperature of the cooling medium in conjunction with the valve can be dispensed with. Preferably, the valve is designed to open the suction line when the actuator has absorbed a certain amount of heat from the cooling medium. The actuator can have a one-way effect shape memory alloy or a two-way effect shape memory alloy. The one-way effect is characterized by a single shape change when a previously deformed actuator is heated.Subsequent cooling does not cause a change in shape, so the actuator must be deformed to close the valve, for example, by a return element. With a two-way effect, subsequent cooling does lead to a corresponding change in shape, returning it to the form it had before heating. The advantage of using a two-way effect shape memory alloy is that the actuator returns to its initial position on its own during cooling and does not need to be moved into this position by a return element. A return element, if provided for the closing element, can therefore be designed more compactly. Preferably, the valve has a return element designed to apply a restoring force to the closing element, acting opposite to the direction of action of the actuator, when the closing element is not in the closed position of the valve.The actuator and / or return element are preferably helically shaped like a helical spring. Instead of a shape-memory alloy, the actuator can have a bimetal, which gives the actuator the property of temperature-dependent expansion and a corresponding change in the position of the closure element, so that the suction line is released when the actuator has absorbed a certain amount of heat from the cooling medium.

[0016] In a further preferred embodiment of the battery module system according to the invention, the degassing device includes a check valve designed to allow fluid flow through the suction line only in one direction, from the battery housing to the suction jet pump. This prevents gas or cooling medium from entering the battery housing. In particular, the check valve is integrated into the suction jet pump and is preferably designed to close the suction line depending on the temperature of the cooling medium. For this purpose, the check valve can have a closing element movable by a temperature-dependent actuator, analogous to the valve described above. Preferably, the valve described above is designed as a check valve.

[0017] In a further preferred embodiment of the battery module system according to the invention, it has a pressure equalization element which is arranged on the battery housing and is designed to enable pressure equalization between the interior of the battery housing and the surrounding environment. The pressure equalization element can compensate for the negative pressure generated in the battery housing by the suction pressure, so that deformation of the battery housing or leakage does not occur. In particular, an inlet of the suction line is arranged at a distance from the pressure equalization element.

[0018] As described above and below, the problem stated at the outset is also solved by a motor vehicle with the features of claim 10. The advantages realized with the battery module system according to the invention can be achieved analogously with the motor vehicle according to the invention. In particular, the battery module is a traction battery of the motor vehicle.

[0019] It is expressly pointed out that the embodiments of the invention described above can each be combined individually or in any technically meaningful combination with each other with the subject matter of the independent claims.

[0020] Variations and embodiments of the invention, as well as further advantages and details of the invention, can be found in the following description and the drawing. The schematic figure shows: Fig. 1 shows an embodiment of a fuel cell system according to the invention.

[0021] Individual technical features of the embodiments described below can also be combined with previously described embodiments as well as the features of the independent claims and any further claims to create objects according to the invention.

[0022] Fig. 1Figure 1 shows an embodiment of a battery module system 1 according to the invention, comprising a battery module 2 with several battery cells 4 arranged in a battery housing 3. The battery module system 1 also includes a cooling circuit 6 designed to cool the battery cells 4 by means of a circulating cooling medium. For this purpose, the cooling circuit 6 has a supply line 62a leading from a cooler 61, which supplies the cooled cooling medium to the battery cells. A heat exchange line section 62c of the cooling circuit 6, provided for cooling the battery cells 4, is designed to be fluid-tight from the interior of the battery housing 3. Furthermore, the cooling circuit 6 has a return line 62b, which returns the cooling medium, heated by the battery cells 4, to the cooler 61. The cooling circuit 6 may include a pump or other conveying device (not shown) that circulates the cooling medium through the lines 62a, 62b, and 62c of the cooling circuit 6.

[0023] The battery module system 1 further comprises a degassing device 7, which is designed to extract gases G that accumulate in the battery housing 3 during operation of the battery cells 4. In this case, the degassing device 7 has a suction line 71 for this purpose, the inlet 71a of which is located in the battery housing 3 and the outlet 71b of which is located outside the battery housing 3.

[0024] The degassing device 7 further comprises a suction jet pump 70, which is configured to generate suction pressure using the circulating cooling medium as a motive medium and to draw the gases G out of the battery housing 3. For this purpose, the outlet 71b of the suction line 71 is fluidly connected to a suction medium inlet of the suction jet pump 70. The degassing device 7 further comprises a valve 72, which is configured to open or close the suction line 71 as required. Preferably, a check valve (not shown) is arranged between the valve 72 and the outlet 71b of the suction line to prevent the ingress of cooling medium into the battery housing.Several pressure equalization elements 5 are arranged on the battery housing 3 and enable pressure equalization between the inside of the battery housing 3 and an environment of the battery housing 3, so that a negative pressure caused by the intake of gases G inside the battery housing can be easily compensated.

[0025] In the present case, the degassing device 7 has two suction jet pumps 70 connected to respective suction lines 71, wherein a first suction jet pump 70 is installed in the supply line 62a of the cooling circuit 6 and a second suction jet pump 70 is installed in the return line, which enables even more effective degassing. In some embodiments, it may be advantageous to provide a suction jet pump alternatively or additionally within the battery housing 3 in the heat exchange line section 62c (not shown).

[0026] The degassing device 7 is configured to supply the gases G to the cooling circuit 6 so that the gases are carried away via the circulating cooling medium. The cooling circuit 6 has a collection vessel 8 configured to collect the gases G carried away by the cooling medium. The collection vessel 8 has a pressure relief valve 9 configured to allow the collected gases G to escape into the environment of the battery module system 1 or into a separate collection container (not shown) once a predetermined internal pressure is reached in the collection vessel 8. Preferably, a cooling medium container 63 of the cooling circuit 6 is simultaneously used as the collection vessel 8 for the carried-away gases G.

[0027] Preferably, the valve 72 is designed to open or close the suction line 71 depending on the temperature of the cooling medium and / or depending on a temperature measured inside the battery housing 3 and / or at predetermined time intervals.

[0028] It should also be noted that "showing" does not exclude any other elements or steps and "a" or "an" does not exclude a multitude.

[0029] The scope of protection of the present invention is defined by the patent claims and is not limited by the features explained in the description or shown in the figures.

Claims

1. Battery module system (1), in particular for a battery cell vehicle, comprising a battery module (2) with a battery cell (4) arranged in a battery housing (3), a (closed) cooling circuit (6) configured to cool the battery cell (4) by means of a circulating cooling medium, and a degassing device (7) configured to extract gases (G) that accumulate in the battery housing (3) during operation of the battery cell (4) from the battery housing (3), wherein the degassing device (7) comprises a suction jet pump (70) configured to generate a suction pressure using the circulating cooling medium as a motive medium and to extract the gases (G) from the battery housing (3).

2. Battery module system (1) according to claim 1, wherein the degassing device (7) is configured to supply the gases (G) extracted from the battery housing (3) to the cooling circuit (6) so that the gases (G) are transported away via the circulating cooling medium.

3. Battery module system (1) according to claim 2, wherein the cooling circuit (6) has a collection container (8) designed to collect the gases (G) transported by the cooling medium.

4. Battery module system (1) according to claim 3, wherein the collection container (8) has a pressure relief valve (9) which is configured to allow the collected gases (G) to escape into an environment of the battery module system (1) or into a separate collection container from a predetermined internal pressure in the collection container (8).

5. Battery module system (1) according to claim 3 or 4, wherein the collection container (8) is a cooling media container.

6. Battery module system (1) according to one of the preceding claims, wherein the degassing device (7) has a suction line (71) with an inlet (71a) in the battery housing (3) and an outlet (71b) fluidly connected to a suction media inlet of the suction jet pump (70).

7. Battery module system (1) according to claim 6, wherein the degassing device (7) has a valve (72) configured to open or close the suction line (71).

8. Battery module system (1) according to claim 7, wherein the valve (72) is configured to open or close the suction line (71) depending on the temperature of the cooling medium and / or depending on the temperature measured inside the battery housing (3) and / or at predetermined time intervals.

9. Battery module system (1) according to one of the preceding claims comprising a pressure equalization element (5) which is arranged on the battery housing (3) and is designed to enable pressure equalization between the interior of the battery housing (3) and an environment of the battery housing (3).

10. Motor vehicle with a battery module system (1) according to one of the preceding claims.

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